The transition towards a sustainable energy future demands the development of low-carbon hydrogen production technologies. This research evaluates and compares the environmental impacts of twelve hydrogen production pathways, based on four key technologies: steam methane reforming (SMR), SMR with carbon capture and storage (SMR-CCS), methane pyrolysis (MP), and polymer electrolyte membrane electrolysis (PEMEL), corresponding to grey, blue, turquoise, and Green Hydrogen. A comprehensive Life Cycle Assessment (LCA) approach was employed, considering regional variations and potential future developments in national energy supply chains. The findings reveal that conventional Grey Hydrogen produced via SMR has the highest climate change impact, with limited potential for decarbonisation. In contrast, Green Hydrogen via PEMEL, particularly when powered by renewable energy, demonstrated the lowest greenhouse gas emissions, although challenges such as water consumption and critical material use must be addressed. Turquoise Hydrogen production through MP showed a lower climate change impact than SMR but resulted in increased impacts in other environmental categories, raising concerns about burden shifting. Blue Hydrogen via SMR-CCS presented a more balanced profile, offering immediate emission reductions with technological maturity, yet its long-term viability is constrained by reliance on fossil resources and the need for large-scale CO₂ storage. The results of Life Cycle Cost analysis show that Green Hydrogen, while environmentally favourable, currently bears the highest Levelised Cost of Energy (LCOE) at €2.23/kWh, primarily due to high capital and operational expenses associated with electrolysis and renewable electricity. In contrast, Grey Hydrogen exhibits the lowest LCOE (€1.38/kWh), benefiting from existing infrastructure and lower upfront costs, while Blue Hydrogen offers a middle ground (€1.92/kWh) by incorporating carbon capture technologies. Sensitivity analyses further reveal that Green Hydrogen is highly dependent on electricity prices, whereas fossil-based pathways are more exposed to natural gas price volatility. These findings reinforce the need for targeted cost reductions—particularly in electrolyser technology—and supportive policy frameworks to enhance the competitiveness of low-carbon hydrogen in future energy systems. Overall, the results highlight the environmental trade-offs associated with each technology and underscore the need for coordinated policy action, technological innovation, and investment in renewable infrastructure to fully realise the potential of Green Hydrogen. The study also emphasises the importance of holistic assessments that extend beyond climate change impacts to support sustainable decision-making. Future research should include social life cycle assessments, detailed case studies, exploration of storage technologies, and comparisons with alternative energy carriers to provide a more comprehensive evaluation of hydrogen’s role in a sustainable energy system.